Some HM language can infer types at the toplevel so you may not have an explicit signature at all, although that's generally frowned upon:

    add1 = map (+1)

OTOH they also split the signature and function "header" so that you don't need to remove the "noise" to get the bare signature e.g.

    add1 :: (Num a) => [a] -> [a]
    add1 = map (+1)